Metal shears and other similar tools may feature bolt-on piercing tips. In metal shears, the piercing tip is a portion at the distal end of the upper or lower jaw of the shear. The piercing tip often experiences a high rate of wear because of the difficult duty it performs in harsh environments. The wear can cause the piercing tip to lose sharpness, which results in more difficult penetration and shearing. The increased difficulty causes the shear to work harder, requiring more energy and lengthening cycle times, which ultimately can reduce the overall efficiency of the shear.
When the piercing tip wears and loses sharpness, it is advantageous to replace the tip. This is facilitated if the piercing tip components are attached to the shear with bolts or other mechanical fasteners. Bolt-on piercing tips have been proposed and implemented on metal shears, and facilitate replacing a dull tip for a sharp one. For example, a bolt-on piercing tip is disclosed in U.S. Patent Application Publication No. 2005/0091852 A1, published on May 5, 2005 (“the '852 publication”). The piercing tip disclosed therein can be removed from the shear jaw by removing the bolts that hold it in place, and replaced with a fresh, sharp tip.
The '852 publication also discloses a piercing tip with multiple shearing edges so the tip can be used more than once. The piercing tip disclosed therein can be detached from the shear jaw, rotated 180 degrees, and replaced on the same side of shear jaw to expose a fresh, sharp shearing edge for use.
However, the piercing tip in the '852 publication still leaves room for improvement. The piercing tip must also protect the jaw of the shear from wear as much as possible. The geometry of the jaw and piercing tip must also resist the forces on the tip during use, without yielding or excessively fatiguing the steel.